Lens-arrayed backlight module and liquid crystal display device

ABSTRACT

The present invention relates to a lens-arrayed backlight module, consisting of a housing, a plurality of lamps, and a plurality of lens plates. The lamps are disposed in parallel between the housing and the lens plates to provide illuminating rays. The lens plates correspond to the lamps respectively, each of which being mounted at the center axis of the corresponding lens plate so that the illuminating rays provided by the lamps diffuse through the lens plates. The present invention also provides a liquid crystal display device using the lens-arrayed backlight module.

This application is a continuation application of pending U.S.application Ser. No. 10/870,969, filed Jun. 21, 2004 (of which theentire disclosure of the pending, prior application is herebyincorporated by reference).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a backlight module of a liquid crystaldisplay, and more particularly to a backlight having a lens array toaccelerate light diffusion and to achieve a thin module.

2. Description of Related Art

The liquid crystal display is not self-illuminating and so requires anadditional lamp for providing a display function. Thus, the backlightmodule is one of the key components of the liquid crystal displays. Asthe size of the display panel increases, the edge-light type backlightmodule employing only one single lamp fails to satisfy the large-sizepanel with providing sufficient illumination. In this situation, most ofthe recent large-size panels adopt the direct-light type backlightmodule having a plurality of lamps. Some display parameters such asbrightness, color and power consumption of the liquid crystal displaysrely heavily on the backlight module. The direct-light type backlightmodule has multiple lamps mounted behind the display panel. Also, adiffuser plate is used so that light rays emitting from the respectivelamps are uniformly projected onto the display panel. The quantity ofthe lamps is subject to the luminosity involved in different sizedpanels. In most cases, the direct-light type backlight module is adaptedto the non-portable products such as desktop liquid crystal monitors andliquid crystal televisions. In particular, the liquid crystal televisionrequires large size, wide view angle and high color saturation, andfurther requires a higher brightness than the liquid crystal monitor.Hence, more and more lamps are used.

However, the current display panels adopting the direct-light typebacklight module cause the maximum brightness to occur directly abovethe lamps, resulting in non-uniform luminosity emitting from thebacklight module, that is, dark and faded stripe problem. In general,the dark and faded stripe problem is solved by increasing the spacebetween the lamp and the diffuser plate. This, however, increases thethickness of the backlight module, and does not conform to the currenttrend for a thin-type display panel. Accordingly, there is a strong needfor the direct-light type backlight module to provide an improved modulecapable of speedily and uniformly diffusing light rays emitted from thelamps within a confined space. As shown in FIG. 1, U.S. patentapplication Ser. No. 10/330,593, entitled “Direct-lighting TypeBacklight Unit”, discloses a prior art multiple concave lenses 110disposed on a diffuser plate 100 to speedily diffuse illuminating rays121 from lamps 120 corresponding to the concave lenses 110 and toachieve an reduced thickness of the backlight module. However, each ofthe lamps 120 has to be precisely aligned with the center axis of thecorresponding concave lens 110 to obtain uniform light distribution, andno disclosure is provided as to how the multiple lamps 120 are preciselyaligned with the center axis of the corresponding concave lenses 110. Inaddition, since the market requirement of liquid crystal displays istowards being larger and larger, fabrication of a single large-sizediffuser plate having a plurality of concave lenses 110 after injectionmolding will cause a shrinkage problem. Shrinkage of the large-sizediffuser plate will cause remarkable changes in the dimensions of theplate and misalignment of the lamps 120 respectively with the centeraxis of the concave lenses 110. Hence, it is not easy to fabricate asingle large-size diffuser plate having multiple concave lenses alignedwith the corresponding lamps and stable quality. In practice, it isnecessary to adjust the modes for fabrication, accompanied by complexprocesses and labor-intensive operations. Even so, the uniformillumination effect is rarely achieved.

Therefore, it is desirable to provide an improved lens-arrayed backlightmodule and liquid crystal display device to mitigate and/or obviate theaforementioned problems.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a lens-arrayedbacklight module so that each of a plurality of light sources is able tobe precisely assembled to the center axis of the corresponding diffusionlens to resolve the shrinkage problem of the diffusion lenses andprovide uniform light illumination.

Another object of the present invention is to provide a liquid crystaldevice so as to improve the dark and faded stripe problem that occurs inthe display panels and to provide a thin-profile liquid crystal devicehaving uniform light illumination.

To attain the aforesaid objects, a lens-arrayed backlight moduleaccording to the present invention comprises a housing having aplurality of long positioning walls and a plurality of lateralpositioning walls; a plurality of light sources disposed in parallelwithin the housing to provide illuminating rays, each of the lightsources including a plurality of lateral positioning sidewalls; and aplurality of lens plates corresponding to the light sourcesrespectively, each of the lens plates including at least two longsidewalls; wherein the lens plates are disposed in parallel on a side ofthe housing opposite to the light sources, the light sources are mountedon the center axis of the corresponding lens plates respectively so thatthe illuminating rays provided by the light sources diffuse through thelens plates, the long positioning walls of the housing correspond to thelong sidewalls of the lens plates and the lateral positioning sidewallsof the housing correspond to the lateral positioning sidewalls of thelight sources so as to position the center axis of the lens plates withrespect to the light sources.

To attain the aforesaid objects, a liquid crystal display deviceaccording to the present invention comprises a housing; a plurality oflight sources disposed in parallel within the housing to provideilluminating rays; and a plurality of lens plates corresponding to thelight sources respectively; wherein the lens plates are disposed inparallel on a side of the housing opposite to the light sources, and thelight sources are mounted on the center axis of the corresponding lensplates respectively so that the illuminating rays provided by the lightsources diffuse through the lens plates.

The light source used in a lens-arrayed backlight module according tothe present invention is not specifically defined. Preferably, the lightsources is cold cathode florescent lamp (CCFL). The lens plate used in alens-arrayed backlight module according to the present invention can beany traditional lens assembly capable of diffusing light rays.Preferably, the lens plate is a concave lens assembly or a pair ofprisms. Each of the light sources used in a lens-arrayed backlightmodule according to the present invention has to be precisely mounted atthe center axis of the corresponding lens plate so as to diffuseilluminating rays provided by the plurality of light sources. The lightsources can be positioned in any traditionally known manner. Preferably,each of the lens plates has at least a first positioning component whileeach of the light sources has at least a second positioning componentfor connection to the first positioning component, whereby the pluralityof light sources are fixed to the center axis of the lens platescorresponding to the light sources respectively. More preferably, thefirst positioning component is a protrusion while the second positioningcomponent is a recess capable of engaging with the said protrusion.Alternatively, in a preferred case, the housing has at least a thirdpositioning component and at least a fourth positioning component; eachof the lens plates has at least a fifth positioning component forconnecting to the third positioning component to fix the relativeposition of the housing to the lens plates; and each of the lightsources has at least a sixth positioning component for connecting to thefourth positioning component to fix the relative position of the housingto the plurality of light sources. As such, the light sources areindirectly fixed at the center axis of the lens plates respectively.More preferably, the third positioning component is a long positioningwall on the housing for engaging with the lens plates, the fourthpositioning component is a short positioning wall on the housing forfixedly clamping the light sources, the fifth positioning component is along edge wall for engaging with the lens plate between the longpositioning walls, and the sixth positioning component is a holder forclamping the light sources at the both ends of the light source.

Other objects, advantages, and novel features of the invention willbecome more apparent from the following detailed description when takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a conventional backlight module;

FIG. 2 is a perspective view of a lens-arrayed backlight moduleaccording to a preferred embodiment of the present invention;

FIG. 3 is a perspective view of a liquid crystal display deviceaccording to a preferred embodiment of the present invention; and

FIG. 4 is a perspective view of a lens-arrayed backlight moduleaccording to another preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Preferred embodiments of the lens-arrayed backlight module and theliquid crystal display device will be described with reference to theaccompanying drawings for illustrating the present invention.

Embodiment 1

Referring to FIG. 2, a perspective view of a lens-arrayed backlightmodule according to a preferred embodiment of the present invention isshown. The lens-arrayed backlight module of the present inventioncomprises a housing 10, a plurality of lamps 20 and a plurality of lensplates 30. The housing 10 is used for receiving the lamps 20 and thelens plates 30. In this preferred embodiment, the lamps 20 arepreferable cold cathode florescent lamps (CCFLs) and disposed inparallel within the housing 10 and mounted between the housing 10 andthe lens plates 30 to provide illuminating rays. Each of the lens plates30 corresponds to one of the lamps 20. In this preferred embodiment, thelens plate 30 is preferable long concave lens plate. Also, each of thelamps 20 is mounted at the center axis of the corresponding lens plate30 so that illuminating rays provided by the lamps 20 diffuse throughthe lens plates 30 to avoid dark and faded stripes forming on thedisplay panel as a result of the rays concentrically projecting onto thearea of the liquid crystal display panel directly above the lamps 20. Inthis preferred embodiment, each of the lens plates 30 has a through hole31 at the both ends thereof. In addition, the lamp 20 has a holder 22snugly received in a recess 11 of the housing 10 at the both endsthereof so that the lamps 20 are respectively disposed inside thehousing 10. The holder 22 has a protrusion 21 extending into the throughhole 31 so that the lens plate 30 is assembled on the lamp 20 byconnecting the protrusion 21 to the through holes 31. Also, the relativeposition of the lamps 20 to the lens plates 30 is fixed so that each ofthe lamps 20 can be easily disposed at the center axis of each of thelens plates 30. Alternatively, the through hole 31 and the protrusion 21are formed vice-versa, that is, the through hole 31 is defined in theholder 22 while two protrusions 21 are respectively disposed at two endsof the lens plate 30 so that the relative position of the lamps 20 tothe lens plates 30 is still fixed.

Embodiment 2

Referring to FIG. 3, a perspective view of a liquid crystal displaydevice according to a preferred embodiment of the present invention isshown. The liquid crystal display device comprises a liquid crystaldisplay panel 40, a housing 50, a plurality of lamps 60 and a pluralityof lens plates 70. The housing 50 is used for receiving the liquidcrystal display panel 40, the lamps 60 and the lens plates 70. In thispreferred embodiment, the lamps 60 are preferable cold cathodeflorescent lamps (CCFLs) disposed in parallel within the housing 50 andmounted between the housing 50 and the lens plates 70 to provide theliquid crystal display panel 40 with illuminating rays. Each of the lensplates 70 corresponds to one of the lamps 60. In this preferredembodiment, the lens plate 70 is preferable a pair of prisms. Also, eachof the lamps 60 is mounted at the center axis of the corresponding lensplate 70 so that illuminating rays provided by the lamps 60 diffusethrough the lens plates 70 to avoid dark and faded stripes from formingon the display panel as a result of the rays concentrically projectingonto the area of the liquid crystal display panel directly above thelamps. In this preferred embodiment, each of the lens plates 70comprises two long sidewalls 701, 702. The housing 50 has twopositioning walls 511, 512 for securely receiving the lens plate 70 in afixed manner and a short positioning wall 52 for fixedly clamping thelamp 60. Also, the housing 50 has two lateral positioning walls 501, 502corresponding to lateral positioning walls 611, 612 of the lamp 60respectively. The relative position of the lamps 60 to the lens plates70 is indirectly fixed by fixing the relative position of the housing 50to the lamps 60, the relative position of the housing 50 to the lensplates 70 and the lateral positioning walls 611, 612 of the lamps andthe lateral positioning walls 501, 502 of the housing, whereby each ofthe lamps 60 can be easily disposed at the center axis of each of thelens plates 70.

Embodiment 3

Referring now to FIG. 4, a perspective view of a lens-arrayed backlightmodule according to another preferred embodiment of the presentinvention is shown. To simplify complication of the manufacture, a houseis preferably to be composition with one large house and a plurality ofsmall houses. Therefore, the lens-arrayed backlight module of thepresent invention comprises a large housing 80, a plurality of smallhousings 85, a plurality of lamps 90 and a plurality of lens plates 95.The large housing 80 has a plurality of elongated openings 81 forfixedly receiving the small housings 85. Each small housing 85 is usedfor receiving a respective lamp 90 and lens plate 95. In this preferredembodiment, the lamps 90 are preferable cold cathode florescent lamps(CCFLs) mounted between the small housings 85 and the lens plates 95 toprovide illuminating rays. In this preferred embodiment, the lens plates95 are preferable long concave lens plates. Also, each of the lamps 90is mounted at the center axis of the corresponding lens plate 95 so thatilluminating rays provided by the lamps 90 diffuse through the lensplates 95 to avoid dark and faded stripes forming on the display panelas a result of the rays concentrically projecting onto the area of theliquid crystal display panel directly above the lamps 90. In thispreferred embodiment, each of the lens plates 95 has a protrusion 96 atthe both ends thereof. In addition, the lamp 90 has a holder 92 snuglyreceived in a recess 86 of the small housing 85 at the both endsthereof. The holder 92 has a through hole 91 extending into theprotrusion 96 so that the lens plate 95 is assembled on the lamp 90 byconnecting the through hole 91 to the protrusion 96. Also, the relativeposition of the lamps 90 to the lens plates 95 is fixed so that each ofthe lamps 90 can be easily positioned at the center axis of each of thelens plates 95. Alternatively, the protrusion 96 and the through hole 91formed vice-versa, that is, the protrusion 96 is defined in the holder92 while the through hole 91 is disposed at the both ends of the lensplate 95 so that the relative position of the lamps 90 to the lensplates 95 is still fixed.

Moreover, multiple thread holes 872, 873 are defined in the largehousing 80 and the small housings 85, respectively. Multiple bolts 871are used to secure the plurality of small housings 85 onto the largehousing 80.

The direct-light type backlight module of the present invention dividesthe prior single large diffuser plate having a plurality of lenses intoa quantity of smaller lens plates for assembly. Thus, the shrinkage rateof the lens plates is reduced so as to revolve the significant shrinkageproblem as associated with the known large diffuser plate in injectionmolding, as well as reducing cost for the diffuser plate mold. Inaddition, in assembling the direct-light type backlight module of thepresent invention, the center of the lamp can be easily aligned with thecenter axis of the lens plate so as to achieve better diffusionefficiency. This invention is capable of uniformly diffusingilluminating rays within a short distance, revolving the dark and fadedstripes formed on the display panel and providing a thin-type liquidcrystal display device having uniform brightness.

Although the present invention has been explained in relation to itspreferred embodiments, it is to be understood that many other possiblemodifications and variations can be made without departing from thespirit and scope of the invention as hereinafter claimed.

1. A lens-arrayed backlight module, comprising: a housing; a pluralityof light sources disposed in parallel within the housing to provideilluminating rays; and a plurality of lens plates disposed in parallelwithin the housing, not only opposite to but also corresponding to thelight sources respectively, the light sources corresponding to thecenter axis of the lens plates respectively so that the illuminatingrays provided by the light sources diffused through the lens plates,wherein the lens plates include at least one first positioningcomponent, which is one of a protrusion and a recess, and the lightsources include at least one corresponding second positioning component,which is the other one of the protrusion and the recess, the firstpositioning component is assembled to the corresponding secondpositioning component so that the light sources are disposed to thecenter axis of the lens plates.
 2. The lens-arrayed backlight module ofclaim 1, wherein the light sources are cold cathode florescent lamps(CCFLs).
 3. The lens-arrayed backlight module of claim 1, wherein eachof the lens plates is a concave lens.
 4. The lens-arrayed backlightmodule of claim 1, wherein each of the lens plates is a pair of prisms.5. A liquid crystal display device, comprising: a liquid crystal displaypanel; a housing mounted on one side of the liquid crystal displaypanel; a plurality of light sources disposed in parallel between thehousing and the liquid crystal display panel to provide the liquidcrystal display device with illuminating rays; and a plurality of lensplates corresponding to the light sources and the liquid crystal displaydevice, the light sources corresponding to the center axis of the lensplates respectively so that the illuminating rays provided by the lightsources diffused through the lens plates first and then project onto theliquid crystal display panel, wherein the lens plates include at leastone first positioning component, which is one of a protrusion and arecess, and the light sources include at least one corresponding secondpositioning component, which is the other one of the protrusion and therecess, the first positioning component is assembled to thecorresponding second positioning component so that the light sources aredisposed to the center axis of the lens plates.
 6. The liquid crystaldisplay device of claim 5, wherein the plurality of light sources arecold cathode florescent lamps (CCFLs).
 7. The liquid crystal displaydevice of claim 5, wherein each of the lens plates is a concave lens. 8.The liquid crystal display device of claim 5, wherein each of the lensplates is a pair of prisms.
 9. The liquid crystal display device ofclaim 5, wherein the housing has a plurality of long positioning wallsand a plurality of lateral positioning walls, the long positioning wallscorresponding to a plurality of long sidewalls of the lens plates andthe lateral positioning sidewalls corresponding to a plurality oflateral positioning sidewalls of the light sources so as to position thecenter axis of the lens plates with respect to the light sources.